| The overall objective of this dissertation is to study the biotransport dynamics and their applications in human transdermal absorption, joint cartilage/synovial fluid interaction, blood flowing through stenosis, leukocyte locomotion within a lab-on-a-chip. To accomplish these goals, computational modeling, Lab-on-Chip fabrication, hormone transdermal absorption testing were applied.;We first started by looking into the problem of transdermal absorption phenomenon. Transdermal drug delivery is a common approach for administration of chemical therapeutic agents. Transdermal absorption is a transport process of drugs through the skin, a multi-laminar structure. The process becomes complicated because of the flux barriers between the interfaces between layers. The finite element method was used to develop a contact algorithm to account for both the influence of the interface barrier and the chemical absorption mechanisms during such a transdermal drug delivery process. The discontinuity at the layer boundary could be presented in the algorithm by adopting residual coefficients to assure the continuity across the interfaces.;We then conducted experimental work by using radioactive 17beta-estradiol to detect the absorptions in stratum corneum, viable epidermis and dermis respectively. Such transdermal parameters as lag time, permeability and diffusion coefficients between the skin and drug were derived.;The next focus is on the blood transport. The hemodynamic shear stress acts as a prevailing factor responsible for arteriosclerosis and thrombosis in blood vessels. We integrated several complex issues including the fluid and structural interaction (FSI), turbulence and non-Newtonian flow into a numerical axisymmetric model for predicting the shear stress and vessel deformation during the blood flow. The leukocyte transportation in a PDMS-microchip was investigated, and a steady laminar CFD solution was used to predict the particle collision and deposition, whereas the FSI algorithm was applied to a vacuum-seal PDMS microfluidic channel for leukocytes locomotion over an engineered substrate. Finally, the FSI method was applied to a joint cartilage model, including both the articular cartilage and subchondral bone, and the synovial fluid. Simulations predicted the shear stress on the articular cartilage by synovial fluid while the subchondral bone experiences forces during movement. |
